Is xlr Y cables ok or a no no?

[Joel Arvidsson]

I you are working say with 2 mono mics fed in to a mixer with two xlr inputs and two xlr outputs. Could you plug in one xlr Y cable in output 1 and another in output 2. Then connect so you get both mics to the red and the other two to a external recorder?

Does this work good or does the xlr Y cabel mess up the audio?

 

[Dave Blackham]

Yes this will work fine.

Just make sure both Red and recorder inputs are ballanced and able to accept the same audio level ie mic or line level. Also make sure phantom pewer os OFF on both Red and the recorder inputs. FYI Red and Epic are both ballanced, Epic accepts mic level only at this time.

 

[Marc Wielage]

You will lose a dB or two with the split, but it's not much loss, as long as it's a mixer output that can be compensated. The other thing you could do is just feed the recorder out to the camera, which is pretty typical. That way, there's no split, because there are active electronics in the recorder.

What you cannot do is split a phantom powered microphone itself going to two different sources. (Actually, you can with an adapter box, but not with just a cable.)

 

[Craig Weeding]

Hello Joel


There are no hard and fast rules for splitting analog audio, (unlike video)


A simple Y cable can work in many situations like the one you describe, the output of a mixer being split to a RED Camera and another external recorder.
The main factors that will determine the success of this technique are ,
1. Output impedance of the mixer being low enough to drive to two inputs with enough current to. With most modern mixers this is not a problem. Output impedance's are more then low enough to properly supply a signal to a RED camera and a external recorder like a Zoom, a Sound Devices, a Nagra, etc...
2. Input impedance of of the devices being high enough to not to load down the output of the mixer. This also is not normally a problem with the input impedance of most devices being high enough not to load down the output of the mixer. A RED camera should not present a problem.
With a little luck and it never hurts to battery power all your units a simple Y cable will often will do the job.


One problem that can pop up is ground loops in the form of hums or buzzes. This is generally due to multiple devices being powered by AC power supplies and one device being better grounded some times causing low level 50 or 60 HZ power to flow via the audio cables connecting the devices. (reason battery power is preferred.)
To deal with this type situation a audio isolation transformer can be used to split the audio instead of a Y cable. the iso transformers also have ground lifts for isolating the ground connection between units.
If you are outputting line level out of you mixer most simple mic splitters may saturate, especially at low frequencies adding distortion. If you use a splitter make sure you use one that can handle line level audio not just mic level
One unit I like is: http://www.posthorn.com/Macvk_5.html
all though the splitters are shielded be sure to keep them away from AC fields given off by item like power supplies, lighting ballast and high current lighting cables.


If you are sending the audio over very long distances (hundreds of meters)you should look at an active Audio DA designed for this type of work, one of the best is made by XTAhttp://http://www.audiocore.co.uk/products-ds800.html


One other strange situation you can run into splitting audio with a Y cable is even though a unit has a balanced XLR cable on it the input may no be actually balanced!


Two problems can occur in this situation

1. if one unit unbalanced and is wired pin 2 hot and the other unit is wired pin 3 hot, the audio will be shorted out and you will at best hear very very low level audio that is unusable. unplug one unit to test and see if this is happening.
2. If one or both units are unbalance and have the same pin hot you will still get a signal but the level will be less then the mixer output, although often usable this is because half the signal is being shorted to ground on the unbalanced device.Also since the signal is no longer balanced you have a greater chance for noise and ground loops

Using the iso transformer will help with both these situations.


Hope this helps


Craig

 

[Tony Koretz]

You will lose a dB or two with the split, but it's not much loss, as long as it's a mixer output that can be compensated. The other thing you could do is just feed the recorder out to the camera, which is pretty typical. That way, there's no split, because there are active electronics in the recorder.

What you cannot do is split a phantom powered microphone itself going to two different sources. (Actually, you can with an adapter box, but not with just a cable.)

Passive splits like this can actually lose up to 6dB. That may not be too much of an issue though. To avoid hums and ground loops etc, it is better to use a transformer equipped splitter if possible. Not sure whether it is still made or not, but the ART Splitcom is a good inexpensive box that does this job pretty well.

 

[Marc Wielage]

No, my understanding is that the loss when combining two outputs is -6 dB (or 1/2 voltage) because the two outputs are driving each other like source impedance. If you're splitting an output into two inputs, and it's a line-level signal, it's not more than a dB or so of loss.

To be sure, I just took the output of an oscillator and fed it straight into a Sound Devices analog 552 mixer and verified a 0VU signal. I then split the signal with a Y-cable to two inputs -- both were still 0. It's probably that the resolution of the meters can't tell a -1dB loss, and I'm guessing that's about what the real-world losses were.

I would be much more reluctant to split a microphone signal because of phantom power issues and so on. Line level output signals, no problem. Feeding a mixer output to a camera and a recorder is not a big deal, assuming shielded cables and short runs. There's always the risk of ground loops and other problems, but that's a common issue. For that reason, I agree that a Y-split is not ideal, but it can work in a case like this. Probably a better choice would be to use a mixer with multiple (dedicated) outputs.

 

[Tony Koretz]

No, my understanding is that the loss when combining two outputs is -6 dB (or 1/2 voltage) because the two outputs are driving each other like source impedance. If you're splitting an output into two inputs, and it's a line-level signal, it's not more than a dB or so of loss.
.

Sorry you are correct. MY mistake. I should have read the question properly. I thought they wanted to split a mic level signal before a mixer, rather than a post-preamp line level signal, which is why I mentioned a possible 6 dB loss. Line level splits are neglible in terms of signal voltage loss.

 

[Marc Wielage]

Yep, that I agree with: splitting a mike signal before a mixer would be very dodgy, since it's a low-level signal and also involves phantom power. I'd be very reluctant to do that under any circumstances.

A 2-way split from a line-level out is not a big deal, though it's a little kludgy and not ideal.

 

[Peter Moretti]

I know this is from four years ago, but it was very helpful to me for a setup I'm working on. THANKS guys!